Cathode ray tube



June 1939. w. ROGOWSKI ET AL 2,161,316

CATHODE RAY TUBE Filed Feb. 12, 1956 fiWen 2 0219: and Wa/Ier Pagan Ski flan} iugw/Beder y Patented June 6, 1939 UNITE STATES E A'EEN E' FFEQE CATHODE RAY TUBE Walter Rogowski, Aachen-Siege],

and Franz Application February 12, 1936, Serial No. 63,564 In Germany February 11, 1935 3 Claims.

It is customary to concentrate or condense the electrons emanating from the cathode of cathode ray tubes. If the anode-cathode voltage is maintained constant the concentration need not be 5 varied during operation and therefore may be adjusted to a predetermined efiiciency, no matter whether magnetic or electric influences serve to produce it. In the case of electrostatic concentration it is possible to provide for such constant efiiciency even if the voltage required for the concentration is given a constant rate with respect to the anode-cathode voltage. Constancy of concentration is desirable especially in the case of sealed ofi tubes.

Experiments however have shown that a constant concentration is not sufficient whenever electron currents of certain high intensities are dealt with. The reason here is that the mutual repulsion of the electrons is in electron-optic relation similar in efiect to a diverging lens, being the more eflicient the stronger the electron current. Therefore, if difierently intense currents of this nature are producing spots of light on a fluorescent screen or the like, these light-spots undergo distortions which are undesired especially in television systems.

This drawback is overcome by the present invention in such a manner that the degree of concentration is made to depend upon the strength of the cathode ray. This may be effected for instance by providing in addition to a predetermined concentration a second concentration which is controlled by the magnitude of the cathode ray.

Since the cathode ray in its turn as regards its strength depends upon the voltage controlling it, it is within the meaning of the invention also to cause such additional concentration to depend upon this control voltage. In such case the control voltage may be caused to influence the additional concentration either directly or over amplifying means.

One embodiment of the invention is described hereafter, reference being had to the accompanying drawing which shows a diagrammatic sectional view of an electron tube as provided by the invention and also shows the circuit arrangement for the parts referred to hereafter.

This tube, whose cathode is designated I and whose anode is denoted by 2, contains a well known system of three electrodes 3, 4, 6 which are in the shape of annular diaphragms. This system serves to concentrate the cathode ray emanating from I and has therefore been designated as an electron-optical condensing lens. Between the electrodes 3, 6 on the one hand and electrode d on the other hand a voltage, the socalled lens voltage, is active which by means of a regulable resistance 8 can be adjusted to a predetermined efliciency with respect to the voltage between cathode l and anode 2. The concentration eiiected by the electrodes 3, 3, 6 is thus independent of the cathode ray. 9 denotes the current source determining the control volt- 10 age for the cathode ray.

In addition to the electrodes 3, 4, 6 and electrode 5 is arranged which like these is in the shape of an annular diaphragm. By a resistance 1 a drop of potential is produced which acts on the elec- 15 trade 5. The concentration due to electrode 5 hence depends upon the cathode ray in such a. manner as to regulate the concentration thereof should this concentration tend to vary. In this way, whenever the cathode ray will increase in 20 intensity the concentrating or condensing action of the system 3, 4, 5, 6 shall increase likewise.

Resistance i may be regulable as shown.

What is claimed is:

1. An arrangement comprising a cathode ray 5 tube having an anode, a fluorescent screen, means for projecting a cathode ray on said screen, means for varying the intensity of said ray in accordance with a control voltage and means for varying the concentration of said ray on said screen in re- 30 sponse to and in the same sense as variations in the anode current of said tube.

2. An arrangement comprising a cathode ray tube having an anode, a fluorescent screen, means for projecting a cathode ray on said screen, means 5 for varying the intensity of said ray in accordance with a control voltage, means for concentrating said cathode ray on said screen independently of the magnitude of said ray and means for varying the concentration of said ray on said 40 screen in response to and in the same sense as the anode current of said tube.

3. An arrangement comprising a cathode ray tube having an anode circuit, a fluorescent screen, means for projecting a cathode ray on said 5 screen, means for varying the intensity of said ray in accordance with a control voltage, a resistance in said anode circuit for producing a voltage drop under action of said control voltage and means for varying the concentration. of said 50 ray on said screen in response to variations in said voltage drop.

WALTER ROGOWSKI. FRANZ AUGUST BECKER. 

